Agent Name

Methylcyclopentadiene dimer

CAS Number




Major Category

Other Classes


3a,4,7,7a-Tetrahydrodimethyl-4,7-methano-1H-indene; 3a,4,7,7a-Tetrahydrodimethyl-4,7-methanoindene; Bis(methylcyclopentadiene); Dimethyldicyclopentadiene; 4,7-Methano-1H-indene, 3a,4,7,7a-tetrahydrodimethyl-; 4,7-Methanoindene, 3a,4,7,7a-tetrahydrodimethyl-; [ChemIDplus] MCPD Dimer; [EPA ChAMP: Hazard Characterization] 2,5-Dimethyl-3a,4,7,7a-tetrahydro-1H-4,7-methanoindene; [ToxPlanet: ECHA REACH Registrations] MCDP; [ExxonMobil MSDS] UN3295


Aliphatics, Unsaturated


Colorless liquid; [CAMEO] Pale yellow liquid with a hydrocarbon odor; [ExxonMobil MSDS]


Used to make fine chemicals; [ExPub: ECHA REACH Registrations] Used as a chemical feedstock; [ExxonMobil MSDS]


May auto-oxidize on exposure to air forming explosive peroxides; [CAMEO] Liquid causes smarting of skin and first degree burns on short exposure; May cause second degree skin burns from longer exposure; Vapor or mist causes eye, mucous membrane, and upper respiratory tract irritation; Inhalation may cause dizziness, difficulty breathing, and loss of consciousness; [CHRIS] Effects to the kidney (increased hyaline droplets in all treated males) and liver (hepatocellular hypertrophy with increased liver weights in females at 100 mg/kg/day and males at 300 mg/kg/day) observed in 28-day oral study of rats; Gross and histopathological changes of the liver and kidney observed in 9-day inhalation study of rats; No reproductive toxicity observed in rats; Developmental toxicity (lower pup birth weight and weight gain) seen in the presence of maternal toxicity in rats; Evidence of neurotoxicity in rats; [EPA ChAMP: Hazard Characterization] Contains 0-0.5% benzene (CAS# 71-43-2) and 0-3.5% dicyclopentadiene (CAS# 77-73-6); A skin and eye irritant; An aspiration hazard by ingestion (may cause lung injury); Harmful by inhalation; [ExxonMobil MSDS] See "Dicyclopentadiene."

Exposure Assessment
Vapor Pressure

14.2 mm Hg

Lethal Concentration

LC50 (rat) > 3,240 mg/m3/4hr

Explanatory Notes

The Guide in the Emergency Response Guidebook is for "Hydrocarbons, liquid, n.o.s."

Adverse Effects

CNS Solvent Syndrome


Hepatotoxin, Secondary


Skin Burns

Links to Other NLM Databases
Toxicity Information


Chemical Information

Search ChemIDplus

Related Information in HazMap

Occupational diseases associated with exposure to this agent: